arnold



G H ARNOLD TELEPHONE RELAY 0E REPBATER.

No. 542,618. Patented July 16, 1895 M, WW

STATESII.

Fries.

CHESTERH. ARNOLD, OF BOSTON, MASSACHUSETTS, ASSIGNOR TO THE AMERICAN BELL TELEPHONE COMPANY, OF SAME PLACE.

TELEPHONE RELAY OR REPEATER.

SPECIFICATION forming part of Letters Patent No. 542,618 dated July 16, 1895.

Application filed March 16, 1895.

To all whom it may concern:

Be it known that I, CHESTER I-I. ARNOLD, residing at- Boston, in the county of Suffolk and State of Massachusetts, have invented cercuits that, while fully responsive to currents originated in either circuit by the transmitters of outlying stations, the current generated by the repeater or due to its operation shall not react upon its own electromagnetic coils.

The invention consists in combining with the twocircuits concerned two local or repeating circuits and two relay or repeater magnets, the said two magnets being in parallel bridges or in parallel branches of the same bridge between the two main conductors of the compound main circuit and each arranged lto act upon one of the local circuits and thereby upon the circuit which at any moment is receiving, both electromagnets, moreover, being responsive to the varying currents of the circuit which at any moment is transmitting.

In the drawings which accompany and form a part of this specification, Figure 1 is a diagram of my invention incorporated in a system of two main circuits joined up to form a compound circuit with the relay or repeater organized, as stated above, at the central or intermediate or repeating station. Fig. 2 is a diagram of a modified mode of arranging the connection of the receiving repeater-magnets.

L and L are the two original main telephone-lines concerned, joined up at the central or repeating station C to form a compound through circuit extending between the two terminal stations AandB and provided therein the usual way with a-transmitter T and a receiver 15, the former being preferably associated, as usuahwith an induction-coil 1, whose primary winding 19 is connected together with Serial No. 542,058. (No model.)

the variable-resistance medium of the transmitter T in the local circuit 0 of the battery or other generator S, and whose secondary winding is included in the main line-circuit.

The main circuits L and L are shown as being metallic circuits, since these are now considered the more desirable, but it is evident that my invention is equally applicable to earth-completed circuits. The circuit L has therefore two conductors 2 and 3 and the circuit L also has two-4 and 5. At the central station the circuits L and L have their respective ends united for through communication, and in that condition they may be regarded either as two independent circuits entering the same station from different directions, arranged with interposed apparatus, whereby each is enabled to repeat into the other, or as a single compound circuit with repeating apparatus placed at an intermediate station, whereby the current of either terminal station is reinforced at the middle of the circuit. Adopting the latter view and considering the organization as a single compound circuit a bridge cl is arranged between the two mains at the points at and y at the central station C, the said bridge being split or divided into branches e and f. In each of the said branches e and f is connected a receiving, relay, or repeating electromagnet R. Two local or repeating circuits D and D are associated with the said repeating-magnets, respectively, and they each contain a source of electrical energy S and a variable resistance medium or relay-transmitter 972. Two induction-coils l and I are also associated with the relay-circuits, the primary winding p of 1 being included in circuit D and the primary p of 1 in the circuit D The secondary winding 5 of 1 is split or centrally divided, one-half being connected on each side of the bridge-junction point a: in the conductors 3 and 5, respectively, and the secondary winding 5 of 1 is similarly divided and in like manner connected in the two opposite conductors 2 and 4 of the said two lines on each side of the bridge-point y.

The variable-resistance medium m of the repeatimgt-circuit D is mounted in operative relation to one of the repeating-magnets R and. is controlled by the vibrations of the armature or diaphragm 70 thereof, the said vibrations being produced in response to Voicecurrents developed by the transmitters at A or B and traversing either L or L", as either may be the message-originatin g circuit. The variable-resistance medium m of the repeating-circuit D is mounted to be actuated or operated by the other relay-magnet in like manner and by a similar mode.

Supposing A to be transmitting, voice-currents traverse circuit L and pass through the bridge d,varying the strength of both repeatermagnets B. These exercise a corresponding variable attraction on their armatures k, and thereby operate the two repeating-transmitters m. The said transmitters in turn throw the currents flowing in the local circuits D and 1) into undulations, vwhich are trans ferred by the induction-coils l and 1 to the main circuits. Since each induction-coil secondary winding is split and the bridge is connected between the two halves of both, it follows that the currents thrown on the main line by the repeater are balanced with respect to the bridge, which, in other words,joins equi-- potential points of the circuit-so far as the relayed currents are concerned, while it is so placed as to be at all times full-y responsive to the transmitter-currents due to the opera- 1. In a telephone relay or repeater system, a compound main line circuit; a double bridge between the conductors of the said main line circuit, each branch thereof containing a repeatin g or receiving magnet; two local repeatin g circ'uits,controlled by the said two receiving magnets respectively; and induction coils having their secondary windings in the two main line conductors respectively, one half on either side of the bridge, and their primaries, included together with variable resistance repeating transmitters in the said local circuits respectively, substantially as described. 4

2. In a telephone repeating system, the combination of two main telephone circuits; two local repeating circuits each including a variable resistance repeating transmitter and a source of current; and two induction coils, having their secondary windings interposed between the two ends of the said two main circuits respectively, so that a compound circuit is formed with a secondary winding in each of its conductors; with a bridge betweenthesaid name to this specificationfln the presence of two subscribing witnesses, this 7th day of March, 1895.

CHESTER H; ARNOLD.

Witnesses:

GEo. WILLIS PIERCE JOSEPH'A. GATELY. 

